1. Field of the Invention
This invention relates to a structure for facilitating the starting and warming of internal combustion engines provided with a carburetor in the main intake passage.
2. Description of the Prior Art
When alcohol, which has a high heat of vaporisation and a low vapor pressure, is used as fuel for an internal combustion engine, it is difficult to generate a combustible gaseous mixture by an ordinary carburetor alone, especially at low temperatures. This poses problems in startability and warming stability of the engine. There is a known structure of this kind in which a heating element such as an electric heater is disposed on the downstream side of the carburetor and adapted to heat the gaseous mixture. When the engine is started at a low temperature, a gaseous mixture generated in the carburetor is heated by the heating element to convert it into a combustible gaseous mixture, and thereby facilitate starting and warming of the engine. In this structure, however, the heating element causes intake resistance during normal engine operation, making it difficult to obtain full engine performance.